Introduction to Concrete – Key Vocabulary

40 vocabulary flashcards summarizing the essential terms and definitions presented in the lecture on concrete materials, properties, production, and handling.

Concrete

A proportioned mixture of cement, aggregates, and water that hardens by hydration into a stone-like mass.

Portland Cement

Hydraulic cement created by burning limestone and clay; the primary binder in modern concrete.

Hydration

The chemical reaction between cement and water that causes concrete to set and gain strength.

Setting

The hardening process of fresh concrete as hydration proceeds.

Mortar

Mixture of cement, water, and fine aggregate (particles < 6 mm) used for plaster or masonry joints.

Plain (Mass) Concrete

Concrete without embedded steel reinforcement.

Reinforced Concrete

Concrete strengthened with embedded steel bars or mesh to resist tensile stresses.

Compressive Strength

The capacity of hardened concrete to resist crushing; primary quality measure of concrete.

Water-Cement (W/C) Ratio

Gallons of water per sack (94 lb) of cement; lower ratios generally yield stronger concrete.

Workability

Ease with which fresh concrete can be mixed, placed, and finished without segregation.

Slump Test

Field test that measures the vertical subsidence (slump) of fresh concrete to assess consistency.

Slump

Vertical drop (in mm or inches) of concrete after removing a standard cone, indicating fluidity.

Durability (Concrete)

Ability of concrete to resist weathering, chemical attack, and wear during service life.

Permeability

Rate at which water or aggressive chemicals penetrate concrete; lower permeability improves durability.

Fine Aggregate

Inert particles smaller than 6 mm (¼ in), typically sand or stone screenings, in concrete.

Coarse Aggregate

Particles larger than 6 mm, such as gravel or crushed stone, providing bulk and strength to concrete.

Special (Lightweight) Aggregates

Materials like expanded shale, vermiculite, or cinders that produce lightweight or insulating concrete.

Waterproofing Compound

Admixture (often calcium stearate or asphalt emulsion) that reduces concrete permeability.

Admixture

Any material other than cement, water, and aggregates added to concrete to modify its properties.

Accelerator

Admixture (e.g., calcium chloride) that speeds up setting and early-age strength gain.

Retarder

Admixture (e.g., calcium lignosulfonate) that slows cement hydration, useful in hot weather.

Air-Entraining Agent

Admixture that forms microscopic air bubbles to improve freeze–thaw resistance and workability.

Plasticizer (Water-Reducer)

Admixture that increases workability at a given W/C ratio or allows lower W/C for same slump.

Fineness Modulus

Numerical index of aggregate particle size distribution used for proportioning fine and coarse aggregates.

Arbitrary Proportioning

Traditional concrete mix design method using fixed volume ratios (e.g., 1 : 2 : 4) without detailed calculations.

Class "AA" Mix

Concrete proportion 1 : 1.5 : 3 (cement : sand : gravel) used for underwater work or retaining walls.

Continuous Mixer

Machine that receives ingredients continuously and discharges a steady stream of mixed concrete.

Drum Mixer

Rotating drum machine commonly used to batch-mix concrete on site.

Hand Mixing

Manual blending of concrete ingredients on a watertight platform; suitable only for small jobs.

Transporting Concrete

Moving fresh concrete from mixer to forms via barrows, buckets, chutes, belts, or pumps within ~30 min.

Formwork

Temporary molds (wood, plywood, steel, plastic) that shape and support fresh concrete until set.

Lumber Forms

Partially seasoned wood boards used as forms; must be braced and oiled to prevent adhesion.

Plywood Forms

Water-proof grade A plywood (≥ 12 mm) used where smooth concrete surfaces are required.

Steel Forms

Reusable metal pans or decking providing accurate shape and smooth finish for concrete elements.

Plastic Forms

Polystyrene or other plastic molds offering lightweight, reusable formwork options.

Shrinkage (Concrete)

Volume reduction of concrete due to drying and temperature changes, often causing cracks.

Contraction Joint

Planned gap or groove in concrete to control cracking from shrinkage or thermal movement.

Curing

Maintaining adequate temperature and moisture in fresh concrete to ensure proper hydration and strength gain.

Curing Compound

Surface-applied chemical film that reduces moisture loss from freshly placed concrete.

28-Day Strength

Standard reference compressive strength measured after four weeks of curing (~60 % of ultimate strength).

Machine Mixing

Mechanical blending of concrete materials, producing more uniform and economical mixes than hand mixing.

Consistency

Degree of fluidity of fresh concrete, ranging from very dry to very wet; assessed by slump test.